Recently, transport robots of a plural substrate-transporting type, in which plural substrates can be transported at the same time, have been developed to raise a processing speed.
FIG. 5 is a plan view for illustrating the content of the prior art in the substrate-transporting method. In the transport robot 10 depicted in this figure, one end of an extendable arm portion 20 is attached to rotary shafts 12a, 12b; and a hand 25 is provided at the other end. The hand 25 possesses first and second mounting portions 15a, 15b; and the first and second mounting portions 15a, 15b are configured such that substrates 16a, 16b may be placed on each of the mounting portions one by one.
When the rotary shafts 12a, 12b and a base 11, on which the rotary shafts 12a, 12b are mounted, rotate, the hand 25 linearly and rotationally moves.
This transport robot 10 is disposed inside a transport chamber 51 of a vacuum processing apparatus 50 of a multi-chamber type as shown in FIG. 6; and the hand 25 on which the substrates are placed is inserted into a processing chamber 542 connected to the transporting chamber 51; and the substrates are placed inside the processing chamber 542.
After a vacuum processing (such as, a thin film formation or the like) inside the processing chamber 542, the hand 25 is inserted into the processing chamber 542; and the substrates are carried out, while placed on the hand 25.
Positions, inside the processing chambers 541, 542, at which the substrates are to be placed, are fixed; and when these positions are taken as first and second processing positions 8a, 8b, the substrates 16a, 16b on the first and second mounting portions 15a, 15b need to be accurately arranged on the first and second processing positions 8a, 8b, respectively.
However, even though either one of the first and second mounting portions 15a, 15b can be aligned to the corresponding processing position 8a, 8b, the distance between the first and second processing portions 8a, 8b and the orientations thereof cannot be completely in conformity with the distance between the first and second mounting portions 15a, 15b and the orientations thereof, due to placement errors or the like. Consequently, both of the first and second mounting portions 15a, 15b cannot be simultaneously aligned to the first and second processing positions 8a, 8b. 
FIG. 5 shows a case where angles θ1, θ2 (θ1=θ2) formed between a linearly moving direction V of the hand 25 and a line segment F1 connecting center points Pa, Pb of the first and second mounting portions 15a, 15b are not equal, by a placement error, to angles φ1, φ2 (φ1=φ2) formed between the linearly moving direction V of the hand 25 and a line segment F2 connecting center points Qa, Qb of the first and second processing portions 8a, 8b. If there is such a placement error, the substrates 16a, 16b on the first and second mounting portions 15a, 15b cannot be accurately placed on the first and second processing positions 8a, 8b at the same time simply by moving the hand 25 through extending or shortening the arm portion 20 and rotating the base 11.
A transport robot is, for example, described in the following document. See No. JP-A 10-275848.